Cap carried axial plug for a fluid dispenser



M r 1967 H. s. DARLINGTON, JR 3,308,999

CAP CARRIED AXIAL PLUG FOR A FLUID DISPENSER Filed Sept. 27, 1965 2 Sheets-Sheet l ATTORNEYS United States Patent Ofiiice 3.3%,999 Patented Mar. 14, 1%67 3,303,999 CAP CARRIED AXIAL PLUG FOR A FLUID DISPENSER Henry S. Darlington, In, Media, Pa., assignor to A. H. Wirz, Inc., Chester, Pa., a corporation of Pennsylvania Filed Sept. 27, 1965, Ser. No. 490,485 2 Claims. (Cl. 222-546) This invention relates to closures for containers and more particularly to caps for metal collapsible tubes.

Collapsible tubes have a wide variety of uses because they are light Weight, shatterproof and can easily expel their contents with a minimum application of pressure to their sidewalls. Because of this case of expulsion, however, it has been necessary to provide tight closure members in order to prevent their accidental discharge. Such tight closures generally include those of the type which are screwed onto the end or tip of the tube by providing threads on the tip and in the cap. However, the necessary machining of the tubes to provide these threaded surfaces creates foreign mater around the tip of the tube which then gets into the interior of the tube and hence into its contents. Whether the tubes are threaded before they are filled or after, minute particles of metal have been found to exist within the contents of the tube. While these minute foreign particles are sometimes unimportant with respect to certain uses of collapsible tubes such as in the dispensing of glue, toothpaste, shampoos, etc., they can represent an extreme hazard where it is important that the presence of foreign material be kept to an absolute minimum such as in the dispensing of ophthalmic ointments. It has thus been necessary to provide a closure member or cap for tubes which will be sufficiently tight and secure to retain the tubes contents against accidental discharge that will require no machining of the tubes neck or tip in order to provide a secure retention between the cap and the tube.

Accordingly, it is an object of this invention to provide a closure member for a tube which will be threadless but yet will be satisfactorily retained against accidental applications of pressure to the sidewalls of the tube.

A further purpose of this invention is to provide a closure member for tubes which will require no machining or other similar operation of the tubes neck, there by reducing the presence of loose particles of metal and other foreign matter.

A further purpose of this invention is to provide a satisfactory closure cap which will satisfactorily grip the tip of the tube without the use of threads.

A further object of this invention is to provide a closure cap for a collapsible tube of an elastomeric composition which is engaged by friction fit with the neck of the tube.

A further purpose of this invention is to provide a closure cap for a collapsible tube that has a smooth tip surface for the dispensing of ophthalmic ointments.

A further object is to provide a cap that is capable of being retained against accidental discharge but yet can be easily removed by the user of the tube with a mere pull or twist of the cap. I

These and other objects of the invention will be readily apparent from the following description of the drawmgs.

FIGURE 1 is a view showing conventional apparatus for the extrusion of a metal collapsible tube, the view showing the relationship between the male and female dies and the knockout plug.

FIGURE 2 shows the apparatus for cutting off the top of the tube formed in the apparatus of FIGURE 1.

FIGURE 3 shows a die block for spinning the orifice of the neck of the tube to provide a rounded end.

FIGURE 4 is an enlarged fragmentary view showing in section the neck of the tube with a bulbous end formed at the tip by the spinning of the tube in an appropriately shaped die block.

FIGURE 5 is an enlarged fragmentary view showing in section the relationship between the tip or neck of the tube and the closure member or cap.

FIGURE 6 is an enlarged fragmentry view showing the reverse taper in the top portion of the cap.

FIGURE 7 shows suitable apparatus for forming the cap.

EGURE 8 shows in section an alternative form for the tip of the tube omitting the bulbous end but still suitable for use with the reverse taper cap.

This invention relates primarily to a tip and cap for a collapsible tube for the dispensing of ophthalmic ointrnents where the tube is to be placed in close proximity to the eye for the dispensing of its contents. Hence the drawings relate to a tip and cap for an ophthalmic ointment tube but it will be understood that the tip and cap can readily be used on any type of collapsible tube.

Referring now to the drawings and in particular FIG- URE 1, there is shown apparatus for the extrusion of a collapsible tube and the neck portion suitable for use in this invention. The female die member 10 includes a die supporting ring 11, and a knockout plug 1.2. A slug of material 13 is placed in the female die and is extruded into the shape of the die by engaging the male die mem her or plunger 14 down into engagement with the cavity in the die 10 thus forming the head and neck of the tube. The plunger 14 is then withdrawn and the extruded tube is knocked out of the die by pushing up on the knockout plug 12 through the bottom of the die. The closed end 16 of the tip of the tube 20 is then removed by rotating the tube on suitable mandrel and while it is being rotated, bringing it into contact with a stationary blade 17. This manner of separating the closed end of the tube substantially prevents the introduction of particles into the interior of the tube.

The tip of the tube is then spun in die block 318, in order to remove its rough edges and to apply a rounded end to the tip of the neck of the tube. The die block is suitably supported by a rubber mount 19. The particular die block shown will produce a straight tip on the neck as shown in FIGURE 8 leaving an orifice 21 but it can alternatively be constructed so as to form the bulbous end 22 as shown in FIGURE 4. The above described method is a conventional method for the formation or" the tip for collapsible tubes and it has been included within this application for completeness as it is desired to provide a tube having a cylindrical neck portion of a certain length with a smooth tip for use with the friction fit closure member or cap according to the obects of this invention.

The closure of cap 24 is suitably an elastomer and can be made of rubber or synthetic rubber or a thermoplastic such as polyethylene having a low, medium or high density. Polyethylene is preferred as it is a fairly soft elastomer and it is not too rigid for use in this invention. The cap may have any outer shape according to the design desired. The cap includes a closed end 26 and an open end 27. Intermediate the ends is a relatively straight section which extends upward to the point 28 as shown in FIGURE 5. The straight section extends downward to point 29 wherein the opening in the cap begins to flare out to accommodate the neck 15 of the tube. This straight cylindrical portion which should be at least inch up to inch and preferably V inch is where the cap engages by friction fit the neck of the tube by expansion of the cap itself. Thus the diameter of the inside of the cap in this area when free from t. e tube must of 3 I necessity be less than the outside diameter of the neck of the tube.

Starting at 28' the inside diameter of the cap has a reverse taper extending to the closed end 26 of the cap, the'top end ,of the cap thus having a greater diameter than the gripping section as shown in FIGURE 6. This reverse taper cooperates with the bulge 19 on the tip of the neck of the tube, gripping behind the enlargement or bulge to provide a secure retention of the cap. The taper should be between'l" and from the axis of the neck of the tube and the cap and preferably around 2. The bulge should extend out approximately .001 inch per side .so as to cooperate with this reverse taper in looking the cap in place: T he taper and the bulbous protrusion canbe of any desired dimension but they should not be of such a size that it renders it difiicult to secure the cap or requires its forced removal when it is desired to empty the contents. They should permit easy. removal of the cap with a slight twist or pull to avoid inconvenience and possible tearing or ripping of the tubes neck. The cap is held by expansion of the elastomer, its resiliency gripping the sides of the neck of the tube at its immediate area.

It will be seen from FIGURE 5 that, as is normal in caps for collapsible tubes, the portion of the cap between closed end 26 and open end 27 constitutes a wall having an inner surface circular in cross section and an outer surface, and whose inner surface imperforately defines a recess whose lower end is the opening in the open end 27 of the cap and whose upper end is the closed end 26 of the cap. In this connection, it will be noted that above, mentioned points 28 and 29 are points on the inner surface of the Wall.

Ophthalmic ointment tubesand tubes of a similar nature have a small outlet orifice not usually exceeding QPPIOXI'. mately .05 inch or a cross sectional area not exceeding approximately .002 square inch. With such small outlets, small pressures are developed at the outlet upon discharge of the tubes contents, and thus there will be a relatively lesser force exerted against the cap than would occur in tubes with larger neck orifices. Because of these small pressures, the frictional fit caps are capable ofholdin g the tubes contents against accidental discharge and hence they are intended for use with small orifice collapsible tubes. The preferred embodiment of this invention includes an enlarged end on the neck of the tube as an additional interlock between the tip and the cap in addition to the frictional gripping of the cap to prevent discharge of the contents. However, because the pressure exerted is small, a straight necked tube without an enlarged end can also be used as the frictional gripping of the cap alone is sufficient to prevent the discharge of the contents. It was found that when the frictional fit'caps constructed according to this invention were placed on ophthalmic tubes having the above orifice size, that the tubes sidewalls burst when pressure was applied to them before the caps were pushed off.

The cap may suitably include an orifice closure 30 at the inner endof the cap in order to seal off the orifice 21 of the neck of the tube and also to position the cap properly withrespect to the tip of the neck.

As will be noted in FIGURE 5, the flaring lower end of the cap is spaced from both the shoulder of the collapsible tube and from the tapering portion of the collapsible tube neck which'is located next to the shoulder. This feature has the advantage that it makes it possible, without the necessity of providing exact uniformity of the pertinent relative dimensions of the cap and the tip-andshoulder portion of the collapsibletube, to insure that a seal is secured between orifice closure 30 and orifice 21 at the other end of the neck. This contributes to the practicality of the present construction as a means ofsecuring an ophthalmic ointment tube with both (1) the requisite freedom from metal particles resulting from. its method of making and at the same time (2) the excellent security of the cap in its on position.

' passage communicating with an outlet in FIGURE 7 shows a method for molding theclosure member although any conventional method for molding elastomers may be used. The molten elastomer is fed along runner 31 and into sprue 32-passing through gate 33 into the die block 34 where it is formed into shape by the upward movement of force pin 35. The sprue 32 is then removed with the elastomer, snapping at its narrowest restriction at gate. 33. The die block-34' isthen raised leaving the cap free after the force pin is retracted into the stripper bushing 36.

By producing a combined tip and cap according to the objectsof this invention an effective closure for ophthalmic collapsible tubes, has been provided whileavoiding the fonmation of metal particles during the manufacture of the tube as in the prior art. By using a parting tool and spinning the end to provide a tip for the dispensing of ophthalmic ointments and while maintaining a straight cylindrical friction fit surface on the neck of the tube, all machine operations, especially threading, which leave minute foreign particles in the interior of the tube have been eliminated.

Except insofar as the context may affirmatively indicate otherwise, words of vertical direction or position concerning the tip or cap herein, including such words in the claims, refer to the direction or position as shown in FIGURE 5. Thus, for example, downward refers to the direction toward the sidewalls and shoulder of the collapsible tube from where the closed end of the cap would be when the capis properly on the neck of the collapsible tube, and upward refers to the opposite direction.

In view of my. invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art,'to obtain all or part of the benefits of my'invention without copying the structure shown, and I therefore claim all such insofar. as they fall within the reasonable spirit and scope of my claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In combination, a collapsible tube for a use which calls for a minimum of foreign particles, whichtube has sidewalls, a shoulder at one end of the sidewalls, and, extending from that shoulder and constituting one end of the collapsible tube,'a tubular neck portion with a central the tip of the neck, the cross sectional area of which outlet does not exceed .002 square inch, said neck tapering inwardly along its outer surface toward the tip to an intermediate point, the neck being cylindrical from said intermediate point to a point just below the tip of the neck, the tip being bulbous in shape and having an outsidediameter at least .002 inch greater than the diameter of the cylindrical portion of the neck, and a cap of flexible materialand havinga closed end, an open end, and a wall extending between theclosed and open end of the .cap, and having an inner surface circular in cross section and an outer surface and by its inner surface imperforately defining a recess whose lower;

end is the opening in the open end of the cap and whose upper end is the closed end of the cap, said recess-defining inner surface of said wall having a cylindrical portion at least .06 inch long positioned intermediate both ends of the cap and of less diameter than and adapted to be engaged by friction fit with at least a circmmferentially continuous part of the outer surface of the aforementioned cylindrical part of theneck of the collapsible tube, said inner surface of said wall tapering outwardly in a down ward direction from the lower end of the cylindrical portion of the inner surface so that the opening in the open end of the cap is wider than the intermediate cylindrical inner surface of the wall, and the inner surface of the wall tapering l to 5 outwardly in the upward direction from the top of the cylindrical portion of the inner surface so that by this outward upward taper the cap will be helpedto be held on the tube by contact at the side toward the neck with the enlarged end in addition to the friction fit between the cylindrical portion of the inner surface of the cap and the neck of the tube, and a conical projection extending from the central portion of the closed end of the cap in the direction of the open end of the cap, the outlet in the tip of the tubular neck having a flaring outer end whose Wider portion is at the outer end thereof and which is adapted to sealingly contact an intermediate portion of the conical projection While leaving free space between said tip and the closed end of the cap around the base of said cone, and the cap, when in fully on position on the collapsible tube, being spaced from both the shoulder of the collapsible tube and the part of the outer surface of the neck already mentioned as tapering inwardly along the outer surface toward the tip to an intermediate point.

2. The combination of claim 1 in which the collapsible tube is for ophthalmic ointment, the cap when off the tube neck is completely unattached to the tube and the outwardly upwardly tapering portion of the inner surface of the cap tapers 2.

References Cited by the Examiner UNITED STATES PATENTS 1,597,421 8/1926 Ball 222-546 X 1,676,846 7/ 1928 Watson 22254'6 X 2,529,836 11/ 1950 Darlington 222-562 X 2,663,463 12/1953 Benbury et al 222546 X 2,690,861 10/ 1954 Tupper 222546 X 2,896,237 7/1959 Owens et al 222-546 X 2,936,935 5/ 1960 Rabb 222-525 ROBERT E. REEVES, Primaiy Examiner. WALTER SOBIN, Examiner, 

1. IN COMBINATION, A COLLAPSIBLE TUBE FOR A USE WHICH CALLS FOR A MINIMUM OF FOREIGN PARTICLES, WHICH TUBE HAS SIDEWALLS, A SHOULDER AT ONE END OF THE SIDEWALLS, AND, EXTENDING FROM THAT SHOULDER AND CONSTITUTING ONE END OF THE COLLAPSIBLE TUBE, A TUBULAR NECK PORTION WITH A CENTRAL PASSAGE COMMUNICATING WITH AN OUTLET IN THE TIP OF THE NECK, THE CROSS SECTIONAL AREA OF WHICH OUTLET DOES NOT EXCEED .002 SQUARE INCH, SAID NECK TAPERING INWARDLY ALONG ITS OUTER SURFACE TOWARD THE TIP TO AN INTERMEDIATE POINT, THE NECK BEING CYLINDRICAL FROM SAID INTERMEDIATE POINT TO A POINT JUST BELOW THE TIP OF THE NECK, THE TIP BEING BULBOUS IN SHAPE AND HAVING AN OUTSIDE DIAMETER AT LEAST .002 INCH GREATER THAN THE DIAMETER OF THE CYLINDRICAL PORTION OF THE NECK, AND A CAP OF FLEXIBLE MATERIAL AND HAVING A CLOSED END, AN OPEN END, AND A WALL EXTENDING BETWEEN THE CLOSED AND OPEN END OF THE CAP, AND HAVING AN INNER SURFACE CIRCULAR IN CROSS SECTION AND AN OUTER SURFACE AND BY ITS INNER SURFACE IMPERFORATELY DEFINING A RECESS WHOSE LOWER END IS THE OPENING IN THE OPEN END OF THE CAP AND WHOSE UPPER END IS THE CLOSED END OF THE CAP, SAID RECESS-DEFINING INNER SURFACE OF SAID WALL HAVING A CYLINDRICAL PORTION AT LEAST .06 INCH LONG POSITIONED INTERMEDIATE BOTH ENDS OF THE CAP AND OF LESS DIAMETER THAN AND ADAPTED TO BE ENGAGED BY FRICTION FIT WITH AT LEAST A CIRCUMFERENTIALLY CONTINUOUS PART OF THE OUTER SURFACE OF THE AFOREMENTIONED CYLINDRICAL PART OF THE NECK OF THE COLLAPSIBLE TUBE, SAID INNER SURFACE OF SAID WALL TAPERING OUTWARDLY IN A DOWNWARD DIRECTION FROM THE LOWER END OF THE CYLINDRICAL PORTION OF THE INNER SURFACE SO THAT THE OPENING IN THE OPEN END OF THE CAP IS WIDER THAN THE INTERMEDIATE CYLINDRICAL INNER SURFACE OF THE WALL, AND THE INNER SURFACE OF THE WALL TAPERING 1 TO 5* OUTWARDLY IN THE UPWARD DIRECTION FROM THE TOP OF THE CYLINDRICAL PORTION OF THE INNER SURFACE SO THAT BY THIS OUTWARD UPWARD TAPER THE CAP WILL BE HELPED TO BE HELD ON THE TUBE BY CONTACT AT THE SIDE TOWARD THE NECK WITH THE ENLARGED END IN ADDITION TO THE FRICTION FIT BETWEEN THE CYLINDRICAL PORTION OF THE INNER SURFACE OF THE CAP AND THE NECK OF THE TUBE, AND A CONICAL PROJECTION EXTENDING FROM THE CENTRAL PORTION OF THE CLOSED END OF THE CAP IN THE DIRECTION OF THE OPEN END OF THE CAP, THE OUTLET IN THE TIP OF THE TUBULAR NECK HAVING A FLARING OUTER END WHOSE WIDER PORTION IS AT THE OUTER END THEREOF AND WHICH IS ADAPTED TO SEALINGLY CONTACT AN INTERMEDIATE PORTION OF THE CONICAL PROJECTION WHILE LEAVING FREE SPACE BETWEEN SAID TIP AND THE CLOSED END OF THE CAP AROUND THE BASE OF SAID CONE, AND THE CAP, WHEN IN FULLY "ON" POSITION ON THE COLLAPSIBLE TUBE, BEING SPACED FROM BOTH THE SHOULDER OF THE COLLAPSIBLE TUBE AND THE PART OF THE OUTER SURFACE OF THE NECK ALREADY MENTIONED AS TAPERING INWARDLY ALONG THE OUTER SURFACE TOWARD THE TIP TO AN INTERMEDIATE POINT. 